Case Study Series

Preparation of Aluminum Surfaces for Coating
–Josh Kramlick

Q: How does micro-etching the surface improve coating adhesion?

A: The micro-etching provides additional mechanical anchoring for a cured coating. Additionally, increased surface area from the etching process creates increased molecular interactions via Van der Waal’s forces.

Q: What happens if we have inadequate rinsing of a cleaning chemistry with the capacity to etch the surface?

A: As with all wet processes such as cleaning, passivation, and etching, complete rinsing is critical to stop the surface processes. Residual chemistries can later hydrolyze and resume attack on the surface or interact with environmental air/moisture to generate other imperfections. It is also possible that residual chemistry could interact with the coating itself to cause other defects. Rinsing is key!

Q: How long will the bare metal remain on a newly etched aluminum surface?

A: It’s very dependent on environmental conditions (temperature, humidity) and the alloy itself. The best practice is to always minimize storage time or process delays after intermediate surface treatment.